Some aspects of consolidation for a varved Lake Agassiz clay

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Martin, Richard Terrence
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The purpose of this study was to measure the common characteristics of compression and consolidation that apply to a typical sample of clay from the Lake Agassiz deposit in Winnipeg. In particular, data was required on the effect of testing techniques, the effect of repeated cycles of loading and unloading on a clay, and the general consolidation and compression properties of the clay parallel to both the vertical and horizontal axes of the clay. In order to determine the influence of equipment upon the values, two types of consolidation equipment were used: a consolidometer (oedometer), and a triaxal cell. The effects of different testing techniques were found by varying the testing procedure for the consolidometer... It was found that the results were somewhat unpredictable. Even the initial void ratios of the various specimens cut from the block showed widely varying values. In fact, it was found that two groups of specimens were defined by the initial void ratio: silty ones averaging at 1.58, and clayey ones at 1.75. It was further discovered that the silt affected the consolidation characteristics far more than the compression properties... The comparison of results between consolidometer tests and triaxial tests did not prove to be fruitful, but it was possible to show that the testing procedure has no effect upon the compression properties gained from the consolidometer. No attempt was made to discover how testing techniques affected the consolidation characteristics. It was discovered that cycling caused the hysteresis loops to progress downwards in a fairly regular manner. Moreover, indications were that these loops also flattened a slight amount. Other analyses indicated that the highest load in the cycle had a major influence upon the amount of downward shift of the consolidation curve...